Huerta-Aguilar Carlos Alberto, Srivastava Rajendra, Arenas-Alatorre Jesús A, Thangarasu Pandiyan
School of Engineering and Sciences, Tecnologico de Monterrey, 5718 Atlixcáyotl, 72453 Puebla, Mexico.
Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, Panjab, India.
ACS Omega. 2023 Feb 13;8(8):7459-7469. doi: 10.1021/acsomega.2c06326. eCollection 2023 Feb 28.
The present work demonstrates a simple and sustainable method for forming azo oligomers from low-value compounds such as nitroaniline. The reductive oligomerization of 4-nitroaniline was achieved via azo bonding using nanometric FeO spheres doped with metallic nanoparticles (Cu NPs, Ag NPs, and Au NPs), which were characterized by different analytical methods. The magnetic saturation ( ) of the samples showed that they are magnetically recoverable from aqueous environments. The effective reduction of nitroaniline followed pseudo-first-order kinetics, reaching a maximum conversion of about 97%. FeO-Au is the best catalyst, its a reaction rate ( = 0.416 mM L min) is about 20 times higher than that of bare FeO ( = 0.018 mM L min). The formation of the two main products was determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS), evidencing the effective oligomerization of NA through N = N azo linkage. It is consistent with the total carbon balance and the structural analysis by density functional theory (DFT)-based total energy. The first product, a six-unit azo oligomer, was formed at the beginning of the reaction through a shorter, two-unit molecule. The nitroaniline reduction is controllable and thermodynamically viable, as shown in the computational studies.
本工作展示了一种由硝基苯胺等低价值化合物形成偶氮低聚物的简单且可持续的方法。4-硝基苯胺的还原低聚反应通过使用掺杂金属纳米颗粒（铜纳米颗粒、银纳米颗粒和金纳米颗粒）的纳米级FeO球经由偶氮键合实现，这些纳米级FeO球通过不同分析方法进行了表征。样品的磁饱和度表明它们可从水性环境中磁性回收。硝基苯胺的有效还原遵循准一级动力学，最大转化率约为97%。FeO-Au是最佳催化剂，其反应速率（k = 0.416 mM L⁻¹ min⁻¹）比裸FeO（k = 0.018 mM L⁻¹ min⁻¹）高约20倍。通过高效液相色谱-质谱联用（HPLC-MS）确定了两种主要产物的形成，证明了通过N=N偶氮键实现了NA的有效低聚。这与总碳平衡以及基于密度泛函理论（DFT）的总能量的结构分析一致。第一种产物，一种六单元偶氮低聚物，在反应开始时通过较短的二单元分子形成。如计算研究所表明的，硝基苯胺还原是可控的且在热力学上可行。
